When should I text him again?

We had a great, long conversation the other day which he was really into... maybe more into than I was. It ended on a positive note. When should I text him again? He isn't a big risk taker, texting is a weakness. I've witnessed the poor baby sit there and try texting someone back (took almost forever.) However, the others day when he and I were texting, I could barely put my phone down before I was receiving another reply. I'm really trying to improve our relationship so When should I and how should I?